This study analyzed the population genetic structure of the black-faced blenny fish along the west coast of Portugal using microsatellite DNA from over 600 fish samples. The results showed high genetic connectivity between sampling locations within 100 km, suggesting limited genetic differentiation at small spatial scales. Some subtle genetic structure was detected between locations, with the Arrábida and Cascais samples more closely related than to the Sines samples. Overall, the study indicates high levels of self-recruitment and gene flow within 100 km for this coastal fish species with limited dispersal capabilities.

1. 90 km
60 km
36 km
Local-scale population structure of the black-faced blenny (Tripterygion delaisi) along the
west coast of Portugal
Farahnaz N. Solomon1 Ester Serrão1, Rita Borges1,2, Serge Planes3
1Center of Marine Sciences, Faro, Portugal
2 Eco-Ethology Research Unit, ISPA – Instituto Universitário, Lisboa, Portugal
3 USR 3278 CNRS-EPHE-UPVD, CRIOBE, Université de Perpignan, France
INTRODUCTION
• 357 adults, 53 juveniles and 215 larvae genotyped over 10 loci; 2 loci (Td3 and Td11) omitted due to null alleles and stuttering
• All samples in HWE and no genotypic linkage disequilibrium
• LOCI CHARACTERISTICS: Highly polymorphic with 268 alleles detected among 8 loci; Range 8(Td7) – 66(Td8); Mean = 33.5±6.8
• GENETIC DIVERSITY: HE high and fairly uniform across all samples with Mean HE= 0.823-0.855; Mean No. of alleles per locus = 18.1-25.9
• PAIRWISE FST values not significant
• ISOLATION BY DISTANCE: No pattern of isolation by distance
• PCoA: See Figure 1
• DAPC: Adults analyzed, k=4 optimal number of clusters; All Samples analyzed, k=6 optimal number of clusters
Comoplots generated did not show any discernible geographic pattern.
Table 1: The number of
Tripterygion delaisi samples
collected by year, life-stage,
location and site as well as
sample code
Population Connectivity:
• “The extent to which discrete populations (larvae, juvenile or adults) are linked by dispersal” [1]
• Important for the design and implementation of Marine Protected Areas
• Population genetic structure is often used to infer the scales and patterns of dispersal that
govern population connectivity, especially in tropical systems
Genetic structure detected at small to medium scales due to:
• Habitat discontinuity [2]
• Environmental heterogeneity i.e. salinity gradients, estuaries, lagoons [3]
• Very specific life history characteristics i.e. direct development, short PLD [3][4][5]
• Can reveal high levels of SELF-RECRUITMENT [9]
• Significant genetic differentiation detected at small spatial scales (<150 km) due to HABITAT
DISCONTINUITY created by deep water and extensive stretches of sand [2]
DATA ANALYSES:
• Genotyping errors, HWE and linkage disequilibrium
• Allele frequencies, diversity parameters (HO HE NA) and inbreeding coefficient FIS
• Pairwise FST values; Test of Isolation by Distance; Principle Coordinates Analyses
(PCoA)
• Identification of genetically similar clusters using DAPC
Adults
Larvae
Juveniles
• Arrábida, Sines and Cascais are highly connected
• Contrasting results to previous studies conducted on this species and other species with similar life history characteristics
• Ocean currents and larval behavior maybe influencing dispersal and connectivity
• Amidst high connectivity Arrábida and Cascais samples appear to be more closely related to each other than to Sines
• Juvenile and larval samples also appear to be distinct from the adult samples.
• Subtle genetic structure - Further examination via more extensive and comprehensive sampling.
REFERENCES: [1] Palumbi, (2003) Ecol Appl. 13(sp1): 146-158 [2] Carreras-Carbonell et al., (2006) Mol Ecol. 15(12): 3527-3539 [3] González-Wangüemert & Vergara-Chen (2014) Helgoland Mar Res. 68(2): 357-371 [4] Hoffman et al.,(2005)
Mol Ecol. 14(5):1367-1375 [5] Hirase et al., (2012) Ecology 33(4): 481-489 [6] Zander, (1986). Tripterygiidae. In Fishes of the North-eastern Atlantic and the Mediterranean Vol. 3: 1118–1121 [7] Borges et al., (2007) Estuar Coast Shelf Sci.
71(3–4): 412-428 [8] Borges et al., (2009) J Coastal Res. (SI56): 376-380 [9] Carreras-Carbonell et al., (2007) Mar Biol. 151(2): 719-727 [10] Carreras-Carbonell et al., (2004) Mol Ecol Notes. 4(3):438-439
ACKNOWLEDGEMENTS: Field Work (Diana Rodrigues, Joao Afonso, Gustavo Franco, Maria Klein, Henrique Folhas), Emanuel Gonçalves; Laboratory Work (Nathalie Tolou, Valentina Neglia)
Funding (MATRIX (PTDC/MAR/115226/2009), REEFISH (PTDC/MAR-EST/4356/2012), MARES)
Figure 1: Plot of the first two axes of the PCoA performed on
pairwise linearized FST values for (a) the “Adults” data set and (b)
“All Samples” data set. The proportion (in percent) of the
variance explained by each axis is given in parenthesis.
• DNA extraction
• 10 microsatellite loci [2][10] amplified in 2 multiplex PCRs per individual using
fluorescently labelled forward primers
• Amplified PCR product screened using an Automated Sequencer
• Alleles sized and scored with the GeneMapper TM software
METHODOLOGY
OBJECTIVES
This study aims to investigate local-scale population genetic structure of Tripterygion delaisi along the west coast of Portugal.
We hypothesize that collections of T. delaisi over a spatial scale of about 100 km along the west coast of Portugal will exhibit limited dispersal and connectivity leading to
significant genetic structure.
SAMPLING
RESULTS
DISCUSSION
1(a)
5 groups detected
ARRABIDA
SINES
CASCAIS
Tripterygion delaisi
• Small demersal fish; abundant in nearshore rocky habitats [6]
• INSHORE DISTRIBUTION of all larval developmental stages [7][8]
• Limited adult mobility and other life-history characteristics (short PLD,
demersal eggs) suggest LOW DISPERSAL CAPABILITIES
STUDY AREA
1(b)
Temporal Variability
SCUBA
LIGHTTRAPS
LABORATORY ANALYSES: